1. Field of the Invention
The present invention relates to a vehicle front-end body structure.
2. Background Art
As recent demands for passenger vehicles, design for the passenger vehicles has been changed such that a deck is placed more forward or a “deck forward design” is adopted so as to expand a space within a passenger compartment. As a result, front side members of the vehicles tend to be shorter in length. Due to this, it is difficult to secure a sufficient impact absorption performance for a vehicle employing a crushable body for absorbing an impact at the time of crash.
For example, as shown in FIG. 3, front side members 100 are provided at a front end of a vehicle body on left and right sides thereof extending in a longitudinal direction of the vehicle. The front side members 100 are bent downwardly at positions directly below or in front of a front deck cross member 102 extending between left and right front pillars 101. The front side members 100 are then bent again to become horizontal so as to be level with a floor surface of the vehicle body.
The design for the front side members 100 allows the surface D of a toe board (or a dash panel) (refer to FIG. 4) to be set at a more forward position of the body thereby to attain an attempt to expand the space in the passenger compartment. On the other hand, the front side members 100 are designed not only to mainly carry input loads generated when the vehicle collides (frontal and offset collisions) but also to collapse in an accordion fashion at front ends thereof to thereby absorb impact energy.
With the front side members 100 constructed as has been described above, however, as shown in FIGS. 4A-4C, there has been a risk that a substantially Z-shaped bending (a Z-bending) (a deformation of the front side member shown in FIG. 4B from a condition illustrated by broken lines to a condition illustrated by solid lines) is easy to be generated by virtue of an input (refer to an arrow in FIG. 4A) when the vehicle collides, whereby the receding distance of the toe board surface D becomes large. Furthermore, in the event that there is made an excessive input when the vehicle collides, there has been a risk that a portion 102 of the floor side member 100 which is disposed underneath a bottom side of the floor panel is buckled, as shown in FIG. 4C. In addition, as a result of the generation of the Z-bending in the front side member 100, there is caused a risk that the crushable length (the length of the portion of the front side member 100 which is designed to collapse in the accordion fashion so as to absorb the impact) of the front side member 100 is reduced, whereby the impact absorption amount is reduced, resulting in an increase in the deformation amount of the passenger compartment (cabin).
To cope with this, JP-A-4-262975 discloses a front-end body structure as follows: In the front-end body structure, in order to increase an impact repulsive force at a portion where the front side member is joined to a dash lower panel and to enhance the energy absorption amount through the plastic deformation of the front side member, an impact load inputted into a front bumper is transmitted from a primary reinforcement member of a radiator core support to a cowl box via a reinforcement portion of a hood ridge panel (the top of a wheel well panel) and a secondary reinforcement member. As a result, the moment around a supporting portion as a fulcrum acts on the secondary reinforcement member.
In the front-end body structure disclosed in the Japanese patent publication, however, the impact input transmission path becomes long (roundabout), and the number of components involved is increased. Accordingly, this calls for a drawback that the front-end body structure becomes complex, whereby the production costs become high.